Absorbent members for absorbent articles using an opened tow of continuous filaments are known. Included is an absorbent member disclosed in Patent Document 1, which has a crimped cellulose acetate fiber tow layer and a ground pulp layer superposed on one side of the tow layer, the two layers being united by pressing in the thickness direction. The absorbent member is described as having improved body fluid spreading properties. However, because cellulose acetate fiber is inferior to pulp in absorbency, a large quantity of ground pulp should be used in combination to secure sufficient absorption capacity. As a result, the absorbent member has an increased thickness, which reduces wearing comfort of the absorbent article.
A tow layer composed of continuous filaments is, however, not favorable in view of properties of wicking a fluid discharged on a skin contacting side in the thickness direction within a limited planar area (hereinafter referred to as “downward wicking properties”).
A cellulose acetate fiber tow layer easily transmits a locally applied force to all over its area. Therefore, the tow layer is destroyed or bunches up easily with the wearer's motion. The absorbent member could be prevented from being destroyed or bunching to some extent by increasing the thickness of the ground pulp layer. In that case, however, the absorbent member would be bulkier, less soft, and less comfort during wear.
Patent Document 2 proposes an absorbent core composed of an upper layer, a lower layer, and an absorbent layer interposed therebetween. The absorbent layer is exemplified by a layer of spread superabsorbent polymer particles on which a fiber layer made of a cellulose acetate fiber tow is disposed. The superabsorbent polymer has a part thereof bonded to the lower layer with an adhesive and another part thereof entering the fiber tow layer. Although part of the superabsorbent polymer enters the fiber tow layer, the most part of the superabsorbent polymer is bonded to the lower layer. In other words, the fiber tow layer and the superabsorbent polymer layer are independent of each other so that the structure of the absorbent core tends to be destroyed when deformed by the wearer's motion during use of the absorbent article.
Known as a technique to prevent side leakage from a disposable diaper is to provide a ridge projecting toward the skin of a wearer on both sides of an absorbent member. However, formation of such ridges makes the production line complicated or increases the production cost.
Apart from these techniques, the assignee of the present invention previously proposed in Patent Document 1 an absorbent article having an absorbent member formed of a great number of small aggregates composed of pulp fiber, a superabsorbent polymer, and hydrophilic fiber having a longer fiber length than the pulp fiber.
Patent Document 1: JP 57-1604574A
Patent Document 2: WO 99/49826A1